Hello! Sorry for taking a few days to get back to this.

Disabling everything at startup has not gained any results, nor has reinstalling the game. Reading around here a bit, I tried limiting the framerate to 60 while still running in DX11 and also updating my video drivers. The lockups are less frequent than they were right after 4.56 landed, but the last time I got one I let it sit and eventually it crashed itself with an 1100002 error(A Fatal DirectX has occurred.) rather than crashing the whole video driver, though I STILL had to restart my PC because everything else was hanging or generally unresponsive. The CPU showed random spikes of activity coming from different programs that shouldn't have had any meaningful effect on anything, such as some of the background/controller software for the Corsair keyboard. Crashes occur even when those processes are manually terminated before playing.

It feels meaningful to note that FFXIV is the ONLY game where this happens - I've had several all day long sessions with other recent releases and none of them cause any trouble, and certainly not to the point where a restart is required.